Enhancement of photocatalytic activity of TiO2 by immobilization on activated carbon for degradation of aquatic naphthalene under sunlight irradiation

Abstract

Remediating and controlling PAHs (Polyaromatic Hydrocarbons) contamination in the environment is essential all over the world. Nano-TiO2 immobilized on large surface area adsorbent is a kind of emerging endeavor to enhance the photo-catalysis performance. In this paper, activated carbon samples (ACs) were synthesized by using a kind of subtropical macroalgae, i.e., Sargassum Horneri (S.H.) as raw material. ACs activated by FeCl3, ZnCl2, a composite activators mixture of FeCl3 and ZnCl2 (CA) were selected to immobilize nano-TiO2 in aquatic environment, and naphthalene degradation performance of these materials was systematically assessed. The results showed that ACs could provide more activated space for naphthalene photocatalytic reaction, in which Zn2+ helped to hold relative high specific surface area, Fe3+ helped to extend the valid light responsive wavelength, and CA could take advantage of both metal ions, with the largest whole volume and surface functional groups. The highest naphthalene degradation efficiency of TiO2/AC-CA under simulated sunlight could arrive to 77.5%, while those of TiO2/AC-FeCl3 and TiO2/AC-ZnCl2 were 65.0%, 54.5%, respectively. Meanwhile, the pH-resistance and reusing capability of TiO2/AC-CA are better than those of other TiO2/ACs. The results helped to clarify the synergistic mechanism of AC and TiO2 in photo-catalysis, especially the metal ions’ role in combining the two materials, and showed the industrial potential of S.H. in PAHs contamination.